Yeah, that hole size is actually okay according to code and standard engineering practices if a few simple rules are followed.
The hole may be no more than 1/3 the actual measured depth of the joist. Figuring that your 2x10 is about 9-1/4 inches deep, you can drill up to a 3 inch hole (WOW!) The hole must have it's edge at least two inches from the bottom or top of the joist, in accordance with IRC R508.2. If the edge of any of their drilled holes ends up closer than 2" to the bottom or top of the joist, they've not only got some 'splaining to do, they owe you a pile of cash. Those holes are also not permitted to be any closer than 2" to any other hole or notch. IF they decided to do two 1" holes, they need to be at least 2" apart (nearest edges, not center to center) in accordance with R508.2.1.
Those holes will cause no special problems when drilled in regular grade stamped lumber. If you have, by off chance, your home constructed of locally sawmilled native lumber, then an engineer has to approve hole sizes and locations. If this is otherwise normal framing lumber bought at the lumber yards, then the paragraph I wrote above is all that will apply.
If you're the sneaky type, let them drill as they please, and if any codes are violated (like drilling too close to the edge) then you just hit the jackpot. If you'd rather be conservative on the matter, print out and review R508.2 of the IRC with them first.
By the way, I'm curious about the joist spacing you quoted. 24" spacing is highly unusual for floor joists. 16" is much more normal, with 12" spacing seen sometimes under rooms that contain things like hot tubs, waterbeds, and pool tables.
"Nothing is foolproof to a sufficiently talented fool"